This invention relates to debarking machines generally referred to as “mechanical ring” debarkers. Debarkers of this type have a ring rotor into and through which successive logs are fed to be engaged and stripped of bark. More particularly, the invention relates to an improved tool, referred to in this application as a “blade” or “debarking blade”, for mechanical ring debarking machines and an improved log debarker that incorporates a novel debarking blade.
In debarking machines of the ring rotor type, several debarking blades are circularly arranged around the central opening of the rotor and extend generally radially inwardly with their cutting edges positioned adjacent the axis of the rotor. As they are rotated by the ring rotor, the blades follow the periphery of the logs while the cutting tips scrape against and remove the bark at the cambium layer. When the rotor is rotated and a log is being fed into the rotor inlet, the end of the log engages the debarking blades and causes them to rotate outwardly so that the each of the climbing edges of the respective blades climbs upwardly onto the peripheral surfaces of the log.
Conventional debarking machines have blades with an “opening edge” or “climbing edge” for the purpose of engaging the end of the log, as described above. Thus, while the climbing edge of the blade guides the blade into the proper position to debark the log, the cutting tip of the blade performs the removal of the the bark as it moves through the debarker. Blades with climbing edges are disclosed in U.S. Pat. No. 2,880,771 (Annis, Jr.); U.S. Pat. No. 3,709,272 (Bowers); U.S. Pat. No. 3,973,607 (Jonsson); and applicant's U.S. Pat. No. 4,280,541.
While such blades are provided with a removable and replaceable cutting tip on the end of the blade, the climbing edges are generally formed of built-up material welded onto the side of the blade and sharpened for use. When worn, the blades are removed from the debarker and either disposed of or returned to a rebuild facility where the climbing edge is removed, new material welded to the side of the blade, and then sharpened. The rebuilt blade is then returned to the user for re-installation on the debarker.
These blades and the manner of rebuilding them is inefficient and wastes time, money and materials. Moreover, because of the angle required for the climbing edge, many such blades are cast in a complex shape necessary to permit the climbing edge to be built up on the blade at the proper angle and with sufficient material to last a relatively long time before repair becomes necessary.